The present invention relates generally to implements for unloading bulk material and more specifically to an implement wherein the side and floor panels are of an improved shock resistant composition having non-stick, low-friction and long-wear characteristics.
Implements for unloading bulk materials, such as manure spreaders, are well known in the art. Conventional manure spreaders include unloading mechanisms having a floor-carried endless chain with transverse slats. The chains and slats are rotated rearwardly to advance the bulk material toward the open end of the implement, whereat a rotating beater reduces the material and throws it from the rear end of the implement. As such implements have increased in size, the chain-type of unloading mechanism has encountered difficulty in moving the volume of material toward the beater mechanism and open end of the spreader. Accordingly, push-off type material discharge mechanisms have been introduced to provide the capability to shift the material and to also improve scraping of the sides of the implement and reduce manual cleaning requirements.
Presently, the sides and floors of such manure spreaders are constructed of steel or wood, both of which present functional and reliability problems. When wood is used for the sides or floors of a manure spreader, as is recommended in U.S. Pat. No. 3,907,211 to O'Reilly, the organic acids and salts present in manure case deterioration. While preservatives are often added to wood to retard such deterioration, it nevertheless occurs with time. Further, the moisture which penetrates wood fibers can increase deterioration. In cold climates where repeated freezing and thawing occurs, the mositure which has penetrated the wood fibers will freeze and then expand. As this moisture, which is generally mixed with solids, freezes and builds up on the walls or floor of the spreader, sliding movement of the bulk material toward the rear of the implement becomes more difficult. On an implement equipped with chains and slats, the slats may jam. If the implement is equipped with a hydraulic ram, it may jam or break if the buildup becomes too great. Occasionally, the shifting mechanism for the ram may be damaged or at least increased downtime will be incurred to break the frozen material from the sides and floor of the implement. Further, wooden sides or walls are less impact resistant after repeated exposures to organic acids or freezing moisture and consequently they often incur damage when frozen manure or other heavy materials are dropped into the implement.
Steel walls and/or floors for manure spreaders better resist impact damages. They nevertheless corrode when exposed to the acids and salts in manure. While copper additives can be added to steel to inhibit rusting, the additional expense merely retards oxidation of the steel. Moisture does adhere to steel and in cold conditions frozen material on the steel walls or floor presents the same problem to movement of a ram or shifting of material toward the back of the box as in a wooden spreader.
One attempt at overcoming the freezing, sticking and deterioration problem is provided in U.S. Pat. No. 4,078,729 Foltz. Foltz has provided an electrically heated floor for his manure spreader to prevent freezing of the liquids during cold weather. Such a solution, however, requires an electrical power source and restricts the usage of the spreader to the locality of that source. Further, the obvious electrical hazard exists.
O'Reilly has provided in U.S. Pat. No. 3,887,153 for a flexible plastic sheet to be mounted on the sides of the implement and arranged to flex during movement of the unloading ram. As the plastic sheet flexes, material frozen to and adhering to it is broken loose. The plastic sheet is less susceptible to corrosion and deterioration than are wood and steel. However, the plastic sheets of O'Reilly are attached to the walls with nails which are subject to corrosion by acids and moisture. Further, the plastic sheets are attached such that moisture can still penetrate between and behind the sheets to permeate the wood. Since O'Reilly has required that the plastic sheet be separated from the wood to assure flexible, moisture and salts can penetrate the wood. Further, O'Reilly has not overcome the problem of assuring a long wear life of the plastic.
In assignee's co-pending application, Ser. No., 966,011, now U.S. Pat. No. 4,220,280, a ram-type manure spreader has been provided with a wooden floor and walls. The wood is covered on opposite sides with plastic. While these side walls and floor surface reduce sticking of the material during sliding movement and unloading of the load, moistures, acids and salts still penetrate the wood between the plastic sheets, requiring that an expensive marine-type grade glue be used between the plies of the plywood to retard and inhibit deterioration of the wall material.